package com.gzsxy.NIO;

import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.util.Arrays;

/**
 * @author xiaolong
 * @version 1.0
 * @description: Scattering：将数据写入到buffer时，可以采用buffer数组，依次写入
 *               Gathering：从buffer读取数据时，可以采用buffer数组，依次读
 * @date 2022/4/25 20:55
 */
public class ScatteringAndGatheringTest {

    public static void main(String[] args) throws Exception{
        ServerSocketChannel serverSocketChannel =  ServerSocketChannel.open();
        InetSocketAddress inetSocketAddress = new InetSocketAddress(7000);
        //绑定端口到socket,并启动
        serverSocketChannel.socket().bind(inetSocketAddress);

        //创建buffer数组
        ByteBuffer[] byteBuffers = new ByteBuffer[2];
        //创建一个Buffer，大小为5，即可以存放5个byte
        byteBuffers[0] = ByteBuffer.allocate(5);
        byteBuffers[1] = ByteBuffer.allocate(3);

        //等客户端连接（telnet)
        SocketChannel socketChannel = serverSocketChannel.accept();
        //假定从客户端接收8个字节
        int messageLength = 8;
        //循环的读取
        while (true){
            int byteRead = 0;

            while (byteRead < messageLength){
                long l = socketChannel.read(byteBuffers);
                //累计读取的字节数
                byteRead += l;
                System.out.println("byteRead=" +byteRead);
                //使用流打印，看看当前的这个buffer的postiton和 limit
                Arrays.asList(byteBuffers).stream().map(buffer ->"postion=" +buffer.position()+", limit="+buffer.limit()).forEach(System.out::println);
                //将所有的buffer进行flip
                Arrays.asList(byteBuffers).forEach(buffer ->buffer.flip());

                //将数据读出显示到客户端
                long byteWirte = 0;
                while (byteWirte < messageLength){
                    long i = socketChannel.write(byteBuffers);
                    byteWirte += i;
                }

                //将所有的buffer，进行clear
                Arrays.asList(byteBuffers).forEach(buffer ->{
                    buffer.clear();
                });
                System.out.println("byteRead=" +byteRead+ "byteWrite" +byteWirte +",messageLength"+messageLength);
            }
        }


    }

}
